In a block based backup, point in time snapshot of a disk or volume is backed up as an opaque stream, providing for efficient copying of data to backup media. To support selective recovery of specific files and/or directories, some block based backup solutions parse and store file system metadata. When a file or directory is requested to be restored, the file system tree is reconstructed to determine which blocks of data are required to be read from backup media and copied to the restore target system.
In an incremental backup, only blocks that have been changed since a last full or incremental backup typically are copied to backup media. For example, disk blocks that have been written to in connection with creating or modifying a file are marked as changed, and when the next incremental backup is done any block marked as having been written to is copied to backup media. In current prior art approaches to performing an incremental backup in a block based backup solution, file system metadata for the entire file system is parsed and stored to backup media, to enable file-by-file recovery.